This application is for fluoroescence spectroscopic equipment that, in combination with the existing facilities for flow cytometry and quantitative fluorescence microscopy, will complete a Fluorescence Center at the University of New Mexico School of Medicine. Specifically, we request funds to purchase a fluorescence spectrophotometer and fluorescence lifetime instrument, the SLM 48000S, along with an accessory stopped-flow module, Biologique SFM3, and two air-cooled lasers (Liconix 4240NB He/Cad and Uniphase 2013-60SL Ar). This instrument system provides maximum versatility for fluorescence analysis: as a steady-state fluorometer it is capable of obtaining corrected fluorescence excitation and emission spectra; as a T-format instrument it is capable of making polarization measurements; as a multiphototube system with fixed excitation, it is capable of simultaneous analysis with up to three separate wavelengths including absorbance; its electronics provide rapid slewing of monochromators to permit additional flexibility in multiwavelength analysis; when its data acquisition system is interfaced to the Biologique SFM3 stopped flow module, it provides fast kinetic analysis of steady-state parameters down to the time-frame of a millisecond; as a phase-sensitive device, it is capable of measuring fluorescence lifetimes and rotational relaxation down to the picosecond time frame. The particular advantage of the SFM3 stopped-flow accessory is its ability to mix small volumes (50 ul) of up to 3 separate reactants under the directions of a computer. The co-PI, Dr. L. Sklar, is an exceptional biophysicist whose research program at Scripps Institute is built in large part on the innovative use of this instrument system. The continuity of his NIH-funded research program on neutrophil activation following his move to UNM depends critically on the availability of this instrumentation. Modern fluorescence spectroscopy is not presently available at the University of New Mexico even though it represents an essential complement to the well-developed techniques of fluorescence flow cytometry and image analysis. Therefore, the incorporation of this instrument system into the Fluorescence Center, together with access to Dr. Sklar's expertise, will significantly enhance NIH-funded research programs focused on receptor-mediated cell activation (Drs. J. Oliver and R. Mandler), enzyme kinetics (Dr. R. Giew) and RNA-protein interactions (Dr. D. Bear). Because spectrofluorometry is basic to all fluorescence technologies, all the current users of the flow and imaging facilities will be secondary users of the spectrofluorometer.